There has been known a technology for screen printing on a curved substrate having a curved surface shape (see, e.g., Patent Literatures 1 and 2). Patent Literature 1 discloses a method in which a screen plate is arranged on an upper portion of a surface to be printed having a curved surface shape and the screen plate is pressed by a squeegee to print the surface to be printed. Also, Patent Literature 2 discloses a curved surface screen printing device configured such that a screen plate is rotationally driven according to the curvature of a surface to be printed so that the screen plate always faces a tangential direction with respect to the surface to be printed.
In the printing method disclosed in Patent Literature 1, the screen plate includes a mesh member made of a metal material such as stainless steel or a resin material such as nylon and polyester. While Patent Literature 1 does not describe by what method the screen plate is fixed, normally, the peripheral edge of the screen plate is fixed to a frame body by adhesion or the like.
In the case where the screen plate is made of a metal material such as stainless steel, since it is harder than the case of a screen plate made of a resin material, even when a clearance with respect to an object to be printed is small, good plate removal can be realized. Therefore, it is suitable for high-precision printing. Meanwhile, when the shape of the screen plate is curved so as to fit the shape of an object to be printed having a curved-surface shape, it is necessary to provide a clearance to the extent that a shape error between the screen plate and object to be printed can be absorbed. However, in the case of the screen plate made of a metal material, as described above, a clearance with respect to the object to be printed cannot be set large because the screen plate is hard. Therefore, a clearance capable of absorbing the shape error cannot be secured.
On the whet hand, in the case where the screen plate is made of a synthetic resin such as nylon and polyester, the screen plate is soft and thus the clearance between the screen plate and an object to be printed can be set large as compared with the case of a metal material. Therefore, when the shape of the screen plate is curved so as to fit the shape of the object to be printed, a clearance to such an extent as to absorb a shape error between the screen plate and object to be printed. However, because the screen plate is soft, a tensile force capable of maintaining the curved state cannot be obtained.
Also, in the curved surface screen printing device of Patent Literature 2, in the case where a surface to be printed is a convex curved surface, the screen plate can be rotationally driven so as to follow the convex curved surface. However, it cannot cope with the case where the surface to be printed is a concave curved surface.